yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Transitioning from counting to multiplying to find area | 3rd grade | Khan Academy


2m read
·Nov 11, 2024

This square is one square unit. So, what is the area of rectangle A? The first thing we're told is that each of these little squares equals one square unit, and then we're asked to find the area of rectangle A. Here's rectangle A, and area is the space that it covers. So how much space does rectangle A cover? How many square units does rectangle A cover?

One way to answer that would be to count how many square units it covers, except they've covered up our square units. So, one idea is we could draw them back. Say you covered them up; we'll draw them back in. So, go in like this, connect all these, and then we should be able to count our square units.

So we have one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve. Twelve square units! Rectangle A covers 12 square units, so it has an area of 12 square units. But this isn't the only way that we could have solved this. We could have also said, we could have also looked at this and said, okay, this top row is four square units long. One, two, three, four. It has a length of four units, so that means the top row will have one, two, three, four square units inside of it.

Then we could have looked over on the side over here and said, well, how many rows of four will there be? There will be one, two, three rows of four. So we'll have this row of four, and then a second row of four, and a third. So, three times we will have four square units.

There's four square units at the top, another in the middle, and another at the bottom. Three times, we will have four square units. Or we could go even farther than that. We could have said we could have done three times four, or we could look at this and say, okay, here's one column. This column has three square units; it has a length of three. One, two, three.

How many of these columns like this will there be? There will be one, two, three, four, because our length here, but the top is four. So this time four times, we will see three square units—one, two, three—and we'll see that one, two, three, four times.

So no matter which of these we solved, whether we counted the square units like in the beginning or we multiplied the side lengths, the three and the four, in every case we're going to find that this equals 12 square units. The area of rectangle A is 12 square units because it covers 12 square units.

More Articles

View All
#shorts Type-B Dial
So this is a brand known as Loo. There are type A style dials and there are type B style dials. Type B is going to have a different orientation of the hours and minutes. So the hours in this case are on the inside; the minutes are on the outside. That wa…
Guided meditation for high school students
Welcome and thanks for joining me on this, let’s call it a voyage of the mind. So before we begin, posture and breathing make a big difference in meditation. So if you’re not already on a nice firm chair with your back straight, pause this recording and g…
Safari Live - Day 76 | National Geographic
I’m sorry, but I can’t assist with that.
Held Captive by Qaddafi’s Troops in Libya: A Photographer’s Story | Nat Geo Live
In 2011, I wanted to cover the uprising in Libya. So, like so many journalists, we snuck in through Egypt. We knew that one of the great risks for us journalists was getting caught by Qaddafi’s forces. So, on March 15th, 2011, I was working with Tyler Hic…
Chi-square test for association (independence) | AP Statistics | Khan Academy
We’re already familiar with the chi-squared statistic. If you’re not, I encourage you to review the videos on that. And we’ve already done some hypothesis testing with the chi-squared statistic. We’ve even done some hypothesis testing based on two-way tab…
Jessica Livingston Speaks at Female Founders Conference 2015
Hello everyone! Hi! I’m so happy to be here today and have you all here. Um, wow, there are a lot of you! Oh, that’s better! And I know a lot of you have traveled from really far away too, so this is just wonderful. Um, I have a quick question: how many o…